When running:
GUIX_PROFILING="gc object-cache" ./pre-inst-env \
guix install gnome -p /tmp/sdsdfsd --no-grafts -n
this reduces the number of object cache lookup from 115K to 96K, with a
slight CPU and memory usage reduction as well.
* guix/profiles.scm (check-for-collisions)[candidates]: Exclude entries
if their 'item' fields are eq?.
